[目的]秸秆常用于养殖业发酵床垫料,用出圈后垫料为主要原料制备的无土栽培基质往往存在保水、透气性差、电导率高等缺陷,限制了其推广应用.本文探讨添加不同比例的生物炭及高吸水树脂(SAP)改善该基质的性能,为促进秸秆资源化利用、提高作物产量提供依据.[方法]以空心菜(Ipomoea aquatica Forsk)为试材进行了盆栽试验.供试基质组成为发酵床垫料堆肥+蛭石+珍珠岩+泥炭(体积比3∶2∶3∶2),其总氮、磷、钾及速效氮、磷、钾养分含量分别为24.2、8.62、10.1、1.94、0.83和3.72 g/kg.在该基质中添加小麦秸秆制成的生物炭(600℃) 2％、4％、6％、8％、10％、12％、14％和16％,以不加生物炭基质为对照,上述基质再裂分为加0.8 g/L SAP和不加SAP两种处理,共18个处理.测定了基质的理化性状,并原位测定了生长过程中基质水分空间分布情况,调查了空心菜的出苗率、生长、养分吸收及产量.[结果]随生物炭添加比例的增加,基质总孔隙度、持水量、pH和电导率显著提高.添加SAP后,基质pH和电导率随生物炭添加比例升高的趋势减缓,导致高比例生物炭(10％～16％)与SAP联合添加的基质pH和电导率显著低于生物炭单独添加处理(P＜0.05).添加SAP后,不同生物炭添加比例下基质的持水量、总孔隙度和通气孔隙度分别增加了13.4％～35.7％、5.8％～10.7％和8.9％～17.9％,且盆钵内水分分布更为均匀,改善了因基质保水性差而造成的水分沉积于盆地的状况.随生物炭添加比例的增加,空心菜出苗率、各项生长指标、根部各项指标和空心菜对氮、磷、钾养分的吸收均表现出先升高后降低的趋势,在10％添加比例下达到最高值,且SAP与生物炭联合添加处理明显高于生物炭单独添加处理.[结论]基质中添加10％的秸秆生物炭可有效改善基质的理化性能并提高空心菜产量,与0.8g/L的SAP配施不仅增强了生物炭的正面效应,同时抑制了高生物炭添加带来的基质pH和电导率的过度升高,二者配施可有效改善基质性能及空心菜的生长状况.%[Objectives] Soilless culture substrates based on wastes of intensive feeding are known for low porosity and water holding capacity,and high electric conductivity,etc.Exploration to improve the properties of them by addition of biochar and super absorbent polymer (SAP) was tried in this paper.[Methods] A pot experiment was conducted using water spinach (Ipomoea aquatica Forsk) as tested materials.The used substrate was prepared by mixing fermented straw bedding compost,vermulite,pearlite and peat in ratio of 3 ∶ 2 ∶ 3 ∶ 2 (v/v),in which the total N,P and K contents were 24.2,8.62,10.1 g/kg,available N,P and K contents were 1.94,0.83 and 3.72 g/kg.Biochar derived from wheat straw (600℃) was added to the substate in ratio of 0,2％,4％,6％,8％,10％,12％,14％ and 16％,and the above substrates were divided into two parts,one part was added with 0.8 g/L of SAP and the other was not added,18 treatments were setup in total.The bulk density,porosity,water holding capacity,pH and electric conductivity (EC) of the treatments were determined.In situ water distribution within the substrates inside the growth pots was determined during growth of water spinach.The emergence rate and some growth parameters of water spinach were measured.[Results] The total porosity,water holding capacity,pH and EC of the substrates were significantly increased with the increase ofbiochar rate,and those in the substrates without SAP addition increased even faster.As a result,the pH and EC in substrates added with SAP were significantly lower than those without SAP addition when the biochar adding rates were higher than 10％ (P ＜ 0.05).In the biochar treated substrates added with SAP,the water holding capacity,total porosity and air porosity rate,growth parameters (plant height,stem diameter,aboveground and belowground fresh/dry weights),root indexes (total length,superficial area,volume,root number) and nutrients (N,P and K) uptakes by water spinach were increased first with the increasing of biochar addition,and reached the maximum at addition rate of 10％,and then decreased when the biochar addition rates were continuously increased.The water spinach growth parameters in the treatments with both biochar and SAP were higher than in those without SAP.[Conclusions] Biochar addition at rate of 10％ could effectively improve physical and chemical properties of the substrates derived from agricultural wastes.Combined SAP addition (0.8 g/L) could enhance the positive effects ofbiochar,and inhibit excessive rise ofpH and EC caused by high biochar addition rates,which is helpful to make better growth substrates and achieve higher yield of water spinach.
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